Oil Watchman Power Tube Batteries

Here’s a little tip for anyone with an Oil Watchman tank gauge. If your batteries run out, you don’t need to spend £30 or so replacing it. You can open the tube and replace the four AAA cells that are inside, it’s a simple job – five minutes if you’re well organised, but allow half an hour if you prefer to take your time.

The power tube is the copper pipe sticking out of the unit that’s on your tank. It has a copper cap on the top, and the whole tube unscrews from the transmitter. You can replace the AAA cells inside simply by twisting off the cap, replacing the batteries, and then twisting the cap back on.

Unscrew the power tube from your transmitter.

Take a large pair of pliers that can grip snugly round the cap. Grip the cap with the pliers as near to the tip as possible (this prevents you from simply squeezing the cap tighter against the tube), and gently twist the cap off. A rubber-coated glove on your other hand might help you grip the tube.

With the cap off, tap the open end of the tube gently on a hard surface and the batteries will come loose. They’re simply Duracell AAA cells, so you can replace them with shop bought batteries (the brand in mine were Duracell Procell, but this is just an industrial brand-name – battery chemistry is the same).

Put the new batteries in, positive-end first. The negative end of the last battery will connect to the cap when you replace it.

Twist the cap carefully back onto the tube, making sure it goes all the way on.

That’s all there is to it. You may want to put some grease on the the batteries as the Watchman manufacturer does; I didn’t bother, particularly since I have a bunded tank. If you want to be doubly sure of your work before screwing the power tube back on, use a multimeter to measure the voltage between the positive and negative contacts on the screw-on connector. You will see at least 6V if all is well, probably 6.5V.

Tips: I used penetrating fluid (WD-40 or similar) under the tube’s cap to help release it. If you still struggle, Brian Glanfield contacted me to suggest the clever idea of sliding a 15mm plumbing nut down the other end of the tube and then using a ring-spanner to hit the nut to knock the cap off. Since the tube is just 15mm copper pipe, it shouldn’t be too difficult to find a suitable nut (wide enough to slide down the tube, but not so wide it slides past the cap).

Someone has uploaded a video on YouTube (link) that shows the dismantled tube and discusses the details of removal and re-assembly (thanks to Jenny Edmunds for the tip-off!).

Note on Oil Watchman Wall Plug

Although my batteries were low, and were overdue replacement, that wasn’t the problem that was preventing me from getting a guage reading. It turned out to be my wall-plug receiver. It was repeatedly showing three horizontal bars followed by the serial number of the device (this is on a barcode-sticker on the underside of the wall-plug, and will match the corresponding number on your tank transmitter).

The device seemed to stop working after a power-cut, and the problem may have been due to a surge when power resumed. This may be a red-herring, but in any case, I will try to make sure I switch the new unit off next time the power goes off.

I was able to order a new Oil Watchman wall-plug from the manufacturer (Sensor Systems/Kingspan Environmental) for £43 all-in price, which I decided to do in spite of the fact that I could get a new Watchman Sonic for just £10 more. I chose to stick with my original Oil Watchman because it has a physical tube to measure fluid depth, and so is much more like a sight-guage, and also because the Sonic’s lithium battery is only expected to last a few years – my Watchman’s batteries were still going after 8 years.

For technically minded, having opened the faulty device, it runs on a PIC chip (PIC16CE624) at 5V, and drives an RF-Solutions AM receiver module. The voltage from the output of the regulator is 5V, and the PIC chip was running fine. My guess is that the receiver circuit failed – either the receiver itself, or the supporting components. The voltage measured across the receiver’s pins was 4.5V, but it wasn’t particularly stable. Just a guess though, I didn’t have the time to look any more thoroughly. It’s a lovely little circuit, however, and has a beautifully simple and efficient AC-DC conversion circuit, so I’ll doubtless tinker with it when I’m bored one evening – even broken stuff has some usefulness in my house!

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112 thoughts on “Oil Watchman Power Tube Batteries”

I have bought a used Titan oil tank that has the Watchman Niveau transmitter fitted, unfortunatelly i do not have the matching receiver.
Will any Watchman receiver work, or does the receiver have a serial number that must match the tanks transmitter ?
Also a thought, if a receiver goes faulty, and the pic ic is ok, i wonder if the pic could be swapped to another receiver ?

You definitely need to match the receiver to the transmitter on your tank. I replaced my receiver after a power-spike killed the previous one, and I had to provide the serial number to the manufacturer so they could flash the PIC.

The PIC will hold the serial number in EEPROM, so while it might be tricky to move to another receiver, it could work to repair a faulty receiver. With a PIC programmer, it might be easier to just read the EEPROM from the broken unit and flash it onto a working one.

I suspected that the serials had to match, even to stop a neighbours transmitters data being “used” on your own (as they use the same frequency) !
I also suspect the manufacturer has set the fuse set in the pic program so only the checksum can be checked, so stopping the pic being copied.

I also do not know if the existing cutout on the tank that fits the Niveau model will be the same for a newer model or different make transmitter/sensor ?

I had thought the EEPROM might have been left readable by a PicKit or whatever, but a quick look at the datasheet suggests it’s only readable by code which I agree will likely be protected.

I’m sure I’ve seen the RF signal from the Watchman transmitter while working on something else – periodic stream of around 300 pulses. I forget the figure, but whatever it was, it was consistent and unlikely to be noise. A bit of fun to be had there – the protocol is probably trivial to figure out.

You’d be easier just replacing the whole thing though – a complete WatchmanSonic might cost about £60 or so if you go back to the manufacturer and explain the situation.

Sorry, the product naming I’d been using was wrong – Niveau is the old style (which I also have) and Watchman Sonic is the new ultrasound one with the Li-ion battery. I edited my replies to avoid confusing anyone else.

I don’t know what the cut-outs are for the Watchman Sonic. The installation manual is here (http://www.sensor-systems.com/help.aspx), so you could check against either a Niveau manual (or just phone their technical line and ask). A drop-in replacement would seem to make commercial sense.

However my decision in a similar situation was to replace the receiver for the Niveau, because I prefer the design – it’s more like a sight-gauge and uses easily replaceable off-the-shelf batteries that last in excess of 5 years. I could have had a new Sonic for about £10 more, but I think I made the right decision, and would recommend anyone do similar. The serial number needed to order a replacement is on the transmitter antenna.

Regarding the reference to the failure after a power fault. I suffered the exact same problem late last year when the power came back on. No problem about getting a replacement from Kingspan though the power company did not want to know even though it was their fault that the power went off, this they admitted to me.
Seems that there is a problem with the receiving unit that is prone to power surge.

Kevin,
As i still have not fitted the titan oil tank yet, i bought myself a used niveau receiver to play with.
Looks like each half of the receiver case is glued/bonded together, when you opened it did you hack saw it, or did you open it another way ?

I think I used a hacksaw on a corner then prised it open. However, the half with the plug-pins on it has a lip, and the cap with the LCD display fits over it – if you can get something under the seal, you may be able to prise it without cutting. The two halves look to have been stuck together with a brittle adhesive.

We have a watchman and the receiver is constantly flashing red with what looks like a ‘r’ on the display…. We have replaced the batteries in the tube as suggested above, but display remains the same….any suggestions? I don’t want to spend £30 odd on a new tube if this is still not going to change display status…. Any suggestions greatly received

When I switch my display on, I get three horizontal bars, followed by 4 digits, then another 4 digits, then it shows ‘r’ with the LED flashing every second or so. It’s waiting for a signal from the transmitter (the tube), but it can take a while before this arrives.

If it doesn’t change after half an hour, then the transmitter is probably either faulty or has no power. The first thing I’d check would be the battery contacts inside the tube, in case a battery leaked and corroded it. I forget how easy/difficult is is to dismantle the copper tube itself – you might have to resort to using a torch to see, and something abrasive on a stick to clean.

Also, try plugging the display into a socket that’s as close as possible to the tank, just to eliminate any chance of the distance or interference preventing the radio signal from getting through.

I would like to thank you for saving me a good deal of money with the helpful tip of replacing the internal AAA’s, mine to were the Duracell batteries and I did have a chuckle now knowing that for £30 you’re getting a copper tube with AAA’s hidden inside.

Excellent advice. However I had to use a flat head screw drive and a tac hammer to gentley tease the cap off little by little. Spot of electrolyte paste and Roberts your mothers brother!

Thanks for sharing your tip. Yep, £30 does sound quite steep, but I guess the cost of providing a custom weather/condensation resistant battery box would also have been quite high – I suppose nobody’s retiring to the Bahamas on that particular revenue stream.

Just used the excellent instructions on here to remove the copper cap but the contents spilt all over the floor! Unfortunately when I put new batteries in they don’t come up to the top of the tube so the cap can’t complete the curcuit. Have I lost a component when the cap came off?

Success! Worked at the second attempt. The spring I found was a little flimsy and I suspect the first time either I hadn’t tamped down the batteries or the spring curled up within the inner (insulated) tube. It’s easy to drift the cap off after all that practice! Existing batteries had ‘best before’ date of 2009 so I suspect they’d been in since tank installation in 2003 for previous owner.

Did you loose the spring from the cap? I had to clamp the tube and after 10 minutes of gentle tapping used the reverse face of an axe! I found both cap and spring but alas after 30 mins am getting the ‘C’ error code for ‘Connection fault’

I recently changed the batteries in my Niveau Watchman power tube after watching a video on Youtube,on the second attempt after making sure the spring was the right way up & the cap was all the way back on, it worked! also after a power cut the display changed to three horizontal bars followed by the serial number,then an r with a red flashing light.I thought it had broken so I tried unscrewing the power tube & then screwed it back on again & this rebooted the system & now it’s working fine again.Hope this helps others users.

Thanks for sharing. I think the sequence of bars, serial-number, and ‘r’ is normal, and should change as soon as a tank signal is received. I usually unplug my receiver as soon as we have a power cut. I’m sure it was a power surge that fried my original receiver.

Despite replacing batteries I could not keep units working for longer than a day. After several attempts with multimeter and TNC T piece adapter I just happened to have, I supply the following tips.
The tube connector is known as a TNC plug. A standard plug requires the knurling filed off. It’s a friction fit to the tube, so it can be pushed out with a rod from the other end of the tube. The original fit plug has a potted metal ring or contact on its rear to mate with the + on the battery. But hidden between the pin of the plug and its rear contact is a 33 ohm 1/4 watt resistor for IS purposes. (Intrinsic safety). In my case there was no solder between the resistor and the pin – so built in obsolescence! I used a standard TNC plug, some 2 part adhesive a nylon insulated spacer to make the assembly. I needlessly Dremel-ed my tube to remove the plug so had to use a jubilee clip to squeeze the cut pipe to make the negative contact to the plug. You do require a soldering iron and something to make the rear contact. Transmitter draws 7 ma at 6 volt

Have just done battery replacement as per helpful comments/video etc after receiver seemed to stick on figure 8 for longer than expected (suspected ‘flat’ batteries in transmitter). However, that hasn’t done the trick (receiver still reading 8) so I’m wondering what to do next. We have had a few power cuts over recent months so perhaps the receiver is knackered? Incidentally, on checking the old battery voltages they didn’t seem all that lower than the new ones.

Try a power off/on at the receiver, but with the power tube unscrewed. Leave for half an hour and check that no reading has been received (display unchanged in this time). Then connect the power-tube and wait for a reading.

If you got an ‘8’ with no power-tube, then the receiver would appear to be faulty. If you only get an ‘8’ with the power-tube connected, then the transmitter may be faulty.

I’d look at the assembly that sinks into the tank – as I recall, there’s a tube with a sensor at the top. I’d assume there would have to be an air hole to prevent the oil being held in the tube by a vacuum, so perhaps check that nothing is preventing the oil in the tube from falling.

Of course, this is assuming there is actually a fault – mine can stay on a high number all summer – readings fall more slowly at higher levels.

Many thanks for the information about the battery replacement. After considerable effort I managed to get the top off of the battery compartment, replaced the batteries and it works perfectly. Really appreciated, as I was already on the trail of a £30 replacement tube! Best wishes, Robin.

Thanks for all the tips, I managed to twist the end off the tube as suggested, it was a bit of a struggle after ten years in the elements. I replaced the four AAA’s with new alkalines and also replaced the end cap with an “off the shelf” 15mm brass compression stop end fitting and some PTFE sealant. All worked in the end but it took about an hour for everything to re-set and work. We live out in the sticks ( hence the oil boiler ) and suffer from between two and ten power cuts a month, over ten years that’s quite a lot, but the sender seems to have survived them all, fingers crossed !

According to the manual, ‘C’ means a connection fault at the transmitter. It does seem to be transmitting, so the batteries appear to be powering the transmitter. Check that the cables are all properly connected inside the tank, and that none of the connectors or cables have been damaged.

hi all
have simular problem with the 3 dash’s and s/n flashing. fault occured with a power cut.
changed battery’s meter reading 6.3 v, removed tube and recaliberated system, refitted tube assy as per fitting instruction’s,note tank is 3/4 full, all to no avail. look’s like i need a replacement assy. any further update’s.

Probably just the plug-in receiver that’s faulty – it costs almost as much to replace as to buy a Sonic version new, but I preferred the technology of the older version, and the batteries are easier to change.

Hi,
My watchman monitor was reading r so i replaced the batteries as suggested and when i re connected the transmitter the monitor was reading the oil level at 2, i thouht i had fixed the problem. When i checked again today the monitor is now flashing C….do you have any sugestions?

The ‘r’ means there’s been no signal received at the wall-plug monitor (maybe the batteries didn’t need changed after all). The manual says that ‘C’ relates to a hardware problem. You should check that any wiring in the tank is properly connected and that the connectors are clean (e.g. mine has a wire between the sensor tube and the transmitter, I believe that some have the sensor tube connected directly to the transmitter).

I was wondering if you could help me. I have recently moved into a house and have an oil tank for the first time. The read out seemed to work perfectly but then after a number of powercuts the read out only showed a couple of lines and not a number. I guess the powercuts have finally done for my niveau watchman.

I tried rebooting the system, by turning the plug off and removing the transmitter.

The readout is now seemingly working again, but is only showing a 4, when I filled the tank up recently and should be reading at least an 8 or 9.

The readout is now flashing low battery. Do you think this is an issue with the watchman, or do you think I have been stiffed by the oil company? I cannot work out how I can look in to check its level. It is covered by heavy undergrowth making it very difficult

It’s unlikely that the oil company ripped you off – you should have received a sheet with the delivered volume and details of the truck’s last calibration. It’s not impossible they mixed up addresses, and have delivered the wrong quantity to you.

If the transmitter is reporting low-battery, then it’s possible that the workings of the sensor are affected, giving inaccurate results. Change the battery and see.

Note, when the receiver is powered up (e.g. after a power cut), then you see what looks like an ‘r’ displayed until a valid signal is received fro the tank. This is normal, and doesn’t suggest a fault.

You can always verify readings manually with a cheap tape measure from B&Q to measure kerosene depth inside the tank, and then do a bit of basic maths, according to your tank dimensions.

Hi all. This site is fab. Followed instructions exactly and my receiver is now getting a reading which is superb! Only prob is that it is showing a 9 when the tank is less than half full. Any of you guys come across this? Perhaps I have not reconnected in the right sequence? ?

Assuming nothing but the batteries have changed (e.g. any wiring and connectors securely reattached), perhaps the batteries themselves are giving too much voltage – are they ordinary alkaline cells, or did you go for lithium? I have read that the no-load voltage of Energizer lithium cells is around 1.8V, which could potentially throw the readings. The transmitter will be close to no-load, since it’s designed as a very low power device.

There’s no mention of the indicator ‘P’ in the manual, but a search of Google suggests a couple of people have seen this before, so perhaps it’s an undocumented fault code.

Try unplugging the wall unit and disconnecting the tank’s power-tube for a couple of hours to see if it recovers – power up the wall unit first, if the error shows up regardless of the transmitter being off, then it could be a faulty wall unit. If the error shows up only after reconnecting the power tube, then it’s probably a faulty transmitter.

Sometimes faults are temperature dependent, so keep an eye on it to see if it recovers during warm periods of the day. In any case, if it turns out to be faulty, call Kingspan, who will probably be able to tell you what’s up.

Can anyone help? my watchman was occasionally flashing ‘C’ but then would resume with the level. I blamed birds going in and out of hedge and maybe interrupting the signal but now has been flashing ‘C’ for some weeks. I have not noticed that the wire which was beneath the power tube (not sure if it is an ariel?) is missing anyone know the name of it so I can search online for a replacement?

I checked my tank’s sensor – I have a bunded tank and there are two wires coming from my transmitter. One is a black length of coax that connects to the depth-sensor, and the other is a white wire that connects to the bund-sensor (a spiky ball that I assume contains a switch that operates if there’s a leak into the bund).

Status ‘C’ means connection fault. The bund sensor wires are joined using bullet connectors, so I suppose these could come loose. It not impossible that deposits could form on the connectors, causing a poor connection. If the bund-sensor wire is completely missing, then it may have fallen to the bottom of the tank. I can’t tell if it can be reattached.

If the wire you’re referring to is the coax for the depth sensor, then it may be broken – it’s difficult to imagine how this connector could work itself off, since it’s much more substantial than the bund sensor wire.

I can confirm that my system faulted to flashing “C” and it was the twin bullet connector from the lead down into the bund that had developed a poor connection. I connected/disconnected a few times to try to clean it up and then all was well.

We have changed the batteries in the copper tube but we get a C on the receiver, we have looked inside the tank but there are no wires, just the long tube and the hole on the side is clear, is the sensor in the bottom of the copper tube where the batteries are or is it somewhere else can anyone help us to locate the sensor. It would be a great help.

Working from top to bottom, there’s the copper tube, which screws into the sensor housing (dark green plastic cylinder) which is screwed onto the tank. Under the sensor housing is a hole in the tank, through which a black plastic tube goes down to near the bottom of the tank. That’s pretty much it. The sensor sends clicks down the black plastic tube, measures the time taken for echoes to return, and calculates the fluid depth.

The version for a bunded tank is slightly different – it has the sensor mounted on the inner tank, and some coaxial cable connects to a transmitter (with similar housing, so it looks very much like the sensor) with the power-tube screwed on. This is really just to allow more flexibility on the transmitter placement.

Many thanks for these instructions (and also to the gentleman who provided the YouTube video). When returning to the house after a power cut I found the receiver showing an r reading and when I removed the original batteries from the power bar I noticed the expiry date was 2010. In my case, after reassembly and reinstalation of the battery pack as per the instructions, the receiver stubbornly remained on a r reading whatever I did. Eventually sorted by disconnecting the battery pack, turning off the receiver and taking out of the socket, wiping the receiver’s plugs with a cloth, reseating the aerial and waiting for 2 mins, plugging that back in and waiting for it to show r, reconnecting the battery pack and leaving for a couple of hours the system started to work again. I don’t know if any of the above contributed or wether it was just a matter of being patient while the receiver acquired the first signal. Anyway £30 saved, thanks very much.

I wonder if you can help. We have a bunded tank and a niveau plus watchman. We’ve changed the batteries and put thh tube back into place. On the second attempt there was a buzzing noise as my husband put the tube back on, and our display worked showing a 6. We thought we’d sorted it out but 24 hours later the display went back to C. We’ve re checked the batteries, spring, etc, and each time, it goes back to C.. Any suggestions?? We haven’t seen any cables that we’d need to check…

The buzzing noise is normal – it’s the ultrasound sensor sending ‘clicks’ to read fluid depth. I’d be looking to clean connectors – with a Niveau Plus there will be a white (on mine at least) wire to a spikey plastic ball lying on the floor of the outer tank (which senses leaked fluid). There’s also a connector between the transmitter (where the battery tube is connected) and the depth sensor. If all this is wired up, and there’s no build-up of corrosion on any of the connectors, then I can’t think what the problem might be.

Hi folks, I need some advice on the wall receiver for Watchman Niveau. The batteries needed replaced, so replaced the four AAS batteries with Durecell Procell in the transmitter tube. Receiver wall socket showed an “r” with red light flashing. Reconnected the transmitter tube and got the level to appear. Job done (or so I thought). 24 hours later, both the fluid level and red light started flashing on receiver wall socket. Tried resetting and level appeared again, it worked fine until 24 hours later. Can anyone please advise why the fluid level and red light are flashing on the wall socket receiver 24 hours after reset?

If the receiver fails to get a signal for a full 24 hours, it flashes to warn you. Check for a clean connection in the screw-on tube connector, make sure all your batteries were fresh (still got the old ones to measure, to make sure none got mixed up?) and that no other wiring came loose while you were working. Also, with some cheap batteries (or eBay rip-offs), the cells can drop voltage quickly in cold conditions.

Excellent article and clever tip sliding a plumbing nut onto the tube to tap off the end cap. Got the whole task completed in about 10 minutes for the cost of 4 AAA Duracell batteries. Great saving on the £38 + vat and delivery that I was about to spend!

I acquired property in early Nov 2014. Watchman Niveau Plus Receiver was showing a steady reading. From early Dec, after some power cuts, the receiver flashes, alternating between a reading and c. however the reading does seem to be accurate and has changed over time, including when new oil was delivered. I changed the power tube batteries for the cost of the 4 batteries following the very useful advice from the site. Whilst I had the power tube unconnected the reading continued as before and also once I had refitted the tube.
I do seem to be getting correct readings but how can I stop the flashing? Should I just try switching off the receiver and then starting it up again or will I need a new receiver?

From memory, I think the manual says that a flashing C indicates a wiring connection problem. I would check that the bund-leak sensor connectors (bullet plugs) are firmly connected and free from corrosion. Since you are getting valid level readings, it would seem likely that other connections are fine.

How do I know if the batteries are running low as Yesterday my RX model was reading 9 on the plugin receiver and today a symbol resembling the letter [ r ] is showing , and I cant find my instruction manual to find out what it means.

This shows when the receiver is waiting for a signal after being switched on. Try plugging it in somewhere closer to the transmitter. The manuals can usually be found with a bit of search engine trawling (tip – include ‘pdf’ in your search terms). I have PDFs somewhere if you draw a blank.

Hi there – quick question, I hope someone can help! I have a lower-case flashing ‘c’, which intersperses with the number ‘7’, which I think is the level of the oil. The instructions say that a display specifically of a ‘capital C’ means connection error and this is definitely a lower case. Also, if there was no connection, presumably it wouldn’t also be showing me (what I assume is) the level.

Connection in this case refers to the wiring of the transmitter assembly – the model of Watchman designed for a double-skin tank has connections for the leak-detector sensor and for the fluid-depth sensor. Since you seem to be receiving tank readings, I’d look at the bullet-plugs that connect the leak-detector. Maybe they’ve accumulated some corrosion or come loose.

After much experience of Haynes manuals in my formative years, I am always a bit sceptical when something is referred to as an easy 5 minute job; but actually this was for me… Watchman unit was installed about 10 years ago and the power tube voltage was down to about 4.6V (4x individual Duracell Procell dated 2012), causing the indicator light to flash and showing intermittent readings. In case it helps anyone, an alternative way to remove the cap is to secure a 15mm ring spanner firmly in a bench vice, slide the power tube into it up to the cap and sharply pull the tube; comes off a treat! Take a little care to line up the cap when refitting, but it goes back on again easily enough with a gentle tap from a mallet. Only problem is what to do with the extra 6 batteries – I bought 10 (the minimum quantity) Industrial Duracell AAA batteries for the princely sum of £2.20.

I have a Watchman Plus which is flashing the upper case ‘C’. Having read the instructions it says there is an internal fault and damage may have occured. Do you know how or if there is anything I can do? Also, I bought our house with this system and do not know where I can this sorted. Is this an oil heating engineer job? Thank you

The ‘C’ denotes a connection fault, so the wiring may be faulty, or perhaps just dirty or corroded connectors. See the other comments for a little more detail.

It’s a fairly simple system, so no need for an engineer unless you really can’t be bothered, in which case I’d start by asking your boiler service engineer. Now is not a bad time to get it serviced, if you’ve just moved in and don’t know the history of your boiler.

I have an apollo ultrasonic receiver and need to replace the battery in the oil tank. All I need is a 3V-CR2430 battery to put in the transmitter, can you please tell me where I can obtain one as they don’t appear to be available in my local shops? Thanks in anticipation of your help.

I have a Niveau unit which has had new batteries a couple of times (btw, worth reminding people to lube them with Vaseline so they come out again) but the latest change has not got rid of the little “r” shape. It did briefly show a 0 despite tank having 800 litres in it; then it showed only the r and a flashing light. Receiver seems OK so am beginning to suspect the sender unit is faulty. Any tips before I order a new one?

Check for build up of corrosion anywhere there’s a connection, and that the batteries are making good contact. The spring on the negative contact needs to be clean, as does the inside of the copper cap that it touches. The kitchen scourer should be good enough. Also, no harm checking that there’s not Vaseline on the battery terminals.

Many thanks for this, just replaced the batteries in my powertube and all is working again..eventually.
Basically After replacing the batteries (exp Mar 2009!) I had it working giving me a reading of 7, being curious I removed the whole unit to see if there was anything that may have caused a C error I get on a hot day, nothing obvious I replaced it and tightened the mounting screws.
Upon switching on the receiver unit I get the r message (awaiting signal) replaced by the C error that took a lot of effort to resolve, I have the version for an UN bunded tank, so just the transmitter with the empty tube below, no other connections.
If anyone else gets the C error after removing /refitting the transmitter from the tank, try loosening the mounting screws a fraction.
This is what my issue was, it would also explain the C error I would get in hot weather as the plastic expanded squeezing the joint and inducing the C error, that would rectify itself upon cooling!
I know this to be the answer as I took the receiver out to the tank on an extension lead whilst returning the C error and loosened the screws a 1/4 turn each, error gone, tighten a 1/4, error returns.
All working now and still secure enough not to allow water ingress.
Anyhow, thanks again and pass it on.

Quite a curious problem & solution. I guess that either the tube squeezing on the ultrasound transducer might add stress to the circuit board or solder joints inside. As far as I can tell, the transmitter case is filled with epoxy, so perhaps stress to the casing is causing stress to the electronics. In any case, interesting information, thanks for sharing.

Now that you have an RFM01 module hooked up for other reasons, are you more tempted by the newer Watchman Sonic devices? They use 433MHz FSK, with a Si4320 chip in the receiver (basically the same as the RFM01).

Have only just found this very informative site. Wondered if anyone has had the same problem as me. My watchman is constantly flashing and registers an upsidedown L all the time. I will be asking my service engineer to fit new battery when he visits soon, the last one only lasted 2years so think I may need to re-place, but as I did not receive a manual when my new tank was delivered complete with watchman in 2007 , I have no way of knowing what this upsidedown L means. Would be grateful if anyone can advise me.

You’re probably seeing what’s meant to be an ‘r’ – this means no signal has been received from the transmitter since switching on the wall-plug display. For testing, I’d temporarily plug it in as close to the tank as possible (maybe even use an extension lead if needed). The tank unit should send a signal within an hour.

I never have a problem with power surges messing up my Watchman plug-in reader – I don’t leave it plugged in! if my tank is filled in say July, I might plug it in sometime in November to check levels – I get the ‘r’ which I interpret as ‘reading’ the level, and once I know I’m OK for a while longer, I unplug it and it goes back in the drawer. We use a socket in the kitchen (nearest the tank) but with a lack of sockets in that area, not leaving it plugged in frees up a socket – and all the while the sender is not talking to the plug I suspect the batteries are dormant also. Naturally I know roughly when to check levels with it being a house we have had for 8 years – early stages I checked more often.

Thanks Kevin for an informative article
I have a bunded tank and have just replaced the batteries and all is back to how it was before
However previously I had the flashing “c” with the number and didn’t realise what to do. I have now checked the bullet connections but the “c” is still flashing with the number.
Do you know if the bund sensor is normally open or closed.
If closed could I short it out at the bullets

[Update]
I shorted it out but there is no change
I suspect that the transmitter is faulty or there is a break between the transmitter and the bullets

My own watchman is also giving me some intermittent problems. It sometimes fails to transmit for more than 24 hours and also gives me a leak-error indicator. It goes back to normal after a few days.

I haven’t figured out if it’s cabling, or something inside the unit, that’s at fault – the epoxy filling makes it tricky to diagnose, but I’ll report back when the milder weather returns and I get a chance to have another look.

I’m not sure about the bund sensor – it may even be an analogue input (resistive?) rather than digital open/closed. I haven’t checked, but if there’s a constant 0V or 5V across the pins, then it’s probably digital. If a periodic voltage is seen on the pins, then it’s analogue (in which case, it may look for specific resistances for all-good, leak-detected, and error values).

Recently bought this property with the monitor already fitted. When plugged in, it was showing the flashing red light and the ‘r’. I purchased a new power tube and successfully fitted it. The receiver then picked up a signal of ‘4’. All seemed ok. However, visited the property a few days ago and I now have 3 horizontal lines on the monitor. Can anyone explain what this means and what can I do to solve it? Thank you.

I seem to recall (though I may be wrong) that this was the symbol that showed when my wall plug failed. I never got to the bottom of exactly what the problem was, but I just bought a new wall plug from Kingspan. Really, the only course of action is to unplug the wall plug & disconnect the powertube and then power it all back up. If that fails, then my guess is that replacement is the only other option. The replacement must match the serial number of the transmitter, so you have to get it through Kingspan. They will probably recommend you buy a Sonic instead, they may be kind enough to credit you for the new powertube if you choose this option.

On a technical note for anyone interested, the PIC chip seemed fine, and I used the RF receiver module in another circuit without problem, so that didn’t seem to be the problem either. There’s little else in the circuit. One possibility is a voltage spike erasing part the EEPROM memory on the PIC chip, or perhaps blowing one of the input pins. The serial number was still showing when the unit was switched on, so at least that part of the EEPROM was still intact.

I contacted Kingspan Customer Services before finding this site
This was there reply

Good afternoon Mr Wiseman

Thank you for your email.
We no longer manufacture your unit. It has been replaced with the Watchman Sonic, a direct replacement for the plus and will fit into the same mounting. This can be purchased locally or from ourselves for £73.00 including vat & p&p

To be fair, they have simply revised their product line and are now making the older products obsolete. It may be that they simply don’t have any saleable parts left for their old products, other than the powertubes that they doubtless feel obliged to continue to produce – I expect there’s still profit to be made on these, but low volume runs to stock up on spare transmitters and wall plugs would be expensive.

The connection between the coaxial cable and the transmitter is broken; for some reason the compression fitting doesn’t unscrew and so I will need a new one and then i will prep the coax. appropriately so as to make a new connection.

Does anyone know the spec of the coax cable and the compression fitting?

I could buy a new watchman sonic but I don’t see the point in throwing it all away if it is just the connection.

Also, the coax cable is tiny so would it be wise to up the spec of the coax section of the system?

For the cable, any 50ohm coax should do (I’d even guess that 75 or 100 ohm cable would work at such a short distance).

I don’t have a part number for the coax connector. However, on a (non plus) transmitter I have, the connector has an external diameter of 9.6mm (11mm including the thread), and 8.5mm or thereabouts internal diameter. I would check Farnell or RS to identify something that looks similar and check the datasheet’s measurement diagram. I’m sure they’re pretty standard parts.

Take care when removing the old cable if the connector is seized on. As I recall, all electronics are embedded in epoxy – if you damage the connector on the unit, then I think it might be difficult to replace.

Since posting the above message, I have done some research on coaxials. I would like to correct my post by saying the connection between the f connection fitting and coaxial is broken. The reason it twists as I suggest is that it is a twist-on variety of f connector – I hadn’t understood this – oops!!

I need to strip the coaxial and prep it to re-establish the connection so I hope this will do the trick! I will give an update in due course…

If anyone knows the spec of the coaxial I would still be interested to know!

Display readout is constantly changing.
I’ve removed the battery pack, replaced the batteries and checked the voltage is OK with the new batteries – but have not yet connected it.
Switched off the receiver and then switched on again.
Every 2 secs I get a flash of the red light, for 4 repeats during which time it displays various digits.
Every 5th repeat the red flash is brighter and longer and is followed by three horizontal bars.
Then repeats the process again, and again….
Have connected the new battery pack but nothing changes.
Assume it’s the transmitter or receiver not working. Any way to check?

I believe something has failed in the receiver. The digits shown in the sequence should correspond to the serial number of your Watchman. You used to be able to get a replacement receiver that is programmed with this serial number, but the price is similar to a new Sonic version, if even available these days.

This happened to me some years back. Technically, the PIC chip that controls everything seems OK, since it is driving the display which is working correctly. The RF receiver module was also tested and worked fine. The DC power supply was seemingly OK too. There’s little else significant on the board. My guess would be that one of the passive components (crystal for the oscillator, a capacitor, etc.) had failed.

Regardless, without a bit of tinkering knowledge and soldering skills, there’s nothing that can be done to fix it.

Firstly thank you for posting this very useful and money saving info. I have a strange problem and thus a couple of questions. I have a watchman Plus on a bunded tank – both new in 2004. From day one, the receiver has flashed a small ‘c’ and the tank reading. I contacted the supplier and they send out a replacement transmitter and receiver – a watchman rather than a watchman plus. Anyway as I was getting correct tank reading in between the flashing c I decided I couldn’t be bothered to mess about in the tank so have just lived with it. A couple of weeks ago we had a power cut – this managed to upset one of the heating system’s programmers and I have a boiler man coming to install the replacement on Thursday. Then we had another power cut a couple of days ago! This seems to have fixed the programmer and affected the Watchman receiver. Like a previous correspondent we frequently have power cuts and the Watchman has never been affected before. Basically it has stopped flashing ‘c’ and is just showing me a steady 5 which is probably about right. If I unplug it, it initialises, flashes red lights and after a while goes to 5 and stays there. So my first question is is this how it should work normally? It never flashes the red light now which makes me think it’s not attempting to find the latest reading – should it? All I can do at the moment is keep an eye on it and see if it drops to 4 which given the temperature just now shouldn’t take more than a couple of days.

Given that it seems to working now should I change the batteries? If it ain’t broke …. but on the other hand these batteries are at least 12 years old now. Can’t believe they’ve lasted this long.

Or should I use the ‘replacement’ watchman they sent me in 2005 after changing the batteries in that one?
And can I replace a watchman plus with a watchman?

Sounds like a cartoonish sequence of events! It does seem to be working as would be expected – it has received a signal and is displaying the level. The ‘c’ is, I think, a connection problem being reported by the bund-leak detector. Can’t imagine why it would incorrectly show an error until after a power cut, perhaps whoever came out to see the programmer checked the wiring, and the second power cut cleared the old error?

The Watchman would be difficult to fit on the tank directly, since the antenna (powertube) doesn’t fit within the outer skin of the tank. Maybe the existing coax cable could be used as an ‘extender’ to bring the powertube/antenna to a suitable place? I forget the connector types on each part of the transmitter – you’d have to have a look.

Still, if you’re confident your readings are valid for your tank, I’d be tempted to just leave exactly as is. If you have a spare Watchman, you can use the spare powertube when the current one finally runs out, giving you plenty of time to replace the batteries in the old tube.

I have a Watchman Plus (Tank Contents Level and Bund Monitoring) fitted to my Titan ES1225B tank – all fitted new in Dec 2006. A few weeks ago the receiver started flashing C, together with a constantly flashing red light. I hoped this was a temporary blip so ignored it (!) – but several weeks on, and despite numerous unplug/replug attempts (in sockets of varying distance from the tank), I still can’t get a reading. This is problematic as the tank has no other means of checking oil level (e.g. an external gauge) so I’m entirely reliant on the Watchman telling me how much oil I have.

In this thread a lot of comments relate to changing the batteries in the copper tube ‘antenna’ – but my Watchman system doesn’t seem to have one. The system is fitted to the inner tank, under the access hatch on the outer tank so I don’t see how an antenna could ever have been fitted as it would clash with the hatch lid. All I can see inside the access hatch is what I think is the top of the transmitter fitted into the inner tank – attached to which is a black cable that runs down into the space between the inner and outer tanks. I think this might be the bund monitor? I took some pictures in the hope that someone could perhaps tell me what’s what – but I can’t see any means of posting pictures here.

So – I don’t know if the reason for the system not showing me how much oil I have is that the batteries need replacing (if so – where are they if I don’t have a copper tube?) or that I SHOULD have a copper tube but it’s fallen off/ been removed during a delivery and lost, or that the system is just broken and I need to replace the whole thing?

Any advice or suggestions would be enormously welcome. Please assume (correctly!) that I have zero DIY knowledge/skills. If any work needs doing beyond simply changing batteries I’ll need to call in a pro to avoid the risk of me blowing me and my neighbours to kingdom come!

The Plus model has two parts that are similar in shape. One is mounted on the inner tank, and has the black cable you mentioned connected to the second part that is the transmitter with the powertube (batteries and antenna combined) screwed into it. Sounds like your transmitter is dangling down the side of the inner tank. Pull this up (carefully, in case it snags on something) and mount it properly.

If the cable comes up empty, then maybe the transmitter is on the floor of the outer tank. A torch and a litter picker might be needed! You can also use a torch to look into your tank to get a rough idea of how empty it is.

Incidentally, Kerosene doesn’t burn anywhere near as easily as, for example, petrol that quickly evaporates explosive fumes and burns vigorously with a mere spark. I’ve read that a lit match falling into a bucket of kerosene would simply go out. Obviously take care because it’s a messy and toxic fuel that would be flammable if soaked into fabric, but don’t worry too much about tank explosions and such.

Thank you SO much for replying so quickly and for taking the time to give me your advice.

I’ve investigated further (ladders and head torches were involved!) and can now just see the transmitter (brass tube type thing) on the inside of the outer tank. Unfortunately, the transmitter is secured to the tank skin on a bracket so I can’t just pull it up to try to replace the batteries and I can’t get at it to work on it in its current position :-(. Even if I could get the transmitter OFF the bracket, I’d have no way of putting it back ON the bracket after I’d (hopefully) fixed it and wouldn’t want to leave it dangling…

It looks like the monitor was fitted before the ‘lid’ of the outer tank was positioned and secured so I suspect this lid needs to be removed before anything can be done about the monitor. That’s too big a job for me (one side of the tank is relatively close to a wall that precludes ladder access and I’m not confident enough to climb onto the tank to release/replace the fittings from above!) so I’m going to have to call in someone to help.

Thank you again for your advice. Although I haven’t fixed the problem at least I now know where everything is on the tank and what I need someone to help me with. I also peeked inside the tank to check the level and have ordered more oil! I really appreciate your help – the internet is a wonderful place sometimes 🙂

If you can reach the bracket with something to prise it off, it’s actually quite weakly secured with soft plastic plugs (and plastic screws as I recall). It doesn’t have to be remounted in the same place.

However, I’d be tempted to simply fit a new monitor to the tank rather than get someone to fix the old one. The monitors themselves are cheaper than labour costs required to get access to the old monitor (unless you’re getting a friend to help, of course).

The oil engineer is coming out to service the boiler next week and is going to ‘have a look’ at the monitor situation for me.

I agree with you – if it’s going to take hours of faffing about to get the old monitor out to replace the batteries and/or fix it (that is, of course, assuming it’s fixable) I’ll just buy a new one, which will hopefully last me 10 years like this one did!

I replaced the batteries in my power tube with standard Duracell batteries but they only lasted about 6 months whereas the originals last 10 year from the time the tank was installed. Is there a better type/brand of battery that should give me longer life please ?

I once read that the industrial Duracell batteries are identical to those that are retailed, and that the colouring is different only to avoid bulk-priced packs being re-sold at retail pricing. That seems plausible to me, since the chemistry is well understood, so I’d guess that fresh Duracells are about as good as you’d get.

I’d check for one bad battery (rare with Duracell, in my experience, but it does happen). I’d also consider whether they came from a reputable source (e.g. not counterfeit), and check their expiry date if possible.

After this, I’d clean the battery terminal connectors and screw threads (spray WD-40 and scrape with an old toothbrush and/or flat screwdriver). Dirt and corrosion can increase resistance, which could show as a lower voltage from the batteries.

Of course, it could also be that the Watchman is faulty and is now simply drawing more current that it should be.

First thank you Kevin for all your help and advice.
I have just replaced the batteries in my power tube, success at the third attempt. I had to use a blunt chisel to get off the cap and found the batteries were a loose fit. On refitting the tube the r signal returned. I searched around on the floor and found the missing cap Spring needed to make the contact. When fitting it it seemed unstable with the point towards the batteries but stable when reversed so I refitted it in the stable position. Again the r signal. Finally I fitted the cap spring with the point towards the batteries. Success is heartwarming. Many thanks.

Hi, Just moved to a house with oil and so its new to me. There is a transmitter on the tank but no receiver. The oil engineer gave me an old unit to try. It seems to flick through some numbers and then stay on’L’. Do I need a new one? thanks

You’ll probably need a completely new sensor. The transmitters and receivers are paired so that the receiver only displays readings from its corresponding transmitter. It used to be possible to buy replacements from Kingspan, where you quote existing the serial number and they send you a suitably configured wall-plug, but I don’t think they do this any more.

It’s quicker and cheaper to just buy a replacement Watchman or Apollo.

If you’re technically minded, and familiar with PIC chips, then there’s some fun to be had attempting to re-program the EEPROM on the unit you were given. However, it’s a bit of a long shot.

Hi. I have the same system. It constantly shows full when it isn’t. Inherited the system when I bought the house. Changed the batteries as suggested (brilliant info thanks). Any ideas. I have. Checked and tubes etc all seem clear and all plugs are working because if you disconnect it shows fault.

Check there’s nothing blocking the ultrasound transducer, which is where the tube joins the transmitter. I suppose that corrosion on the metal disk of the transducer would prevent it from flexing properly, so a torch should help show a nice shiny surface (or not, as the case may be).

Hi ,can I just say what a helpful site!Kevin I have removed the cap from the powertube and replaced the batties.
The sensor is showing three horizontal dashes.I noted the ariel at the top seems loose and twists round easily without tightening.Is this normal.Also is there supposed to be a spring inside the cap of the copper tube?
Thanks.

Since the sender is filled with epoxy, so far as I can tell, there’s not much that can be done practically on the electronics to troubleshoot. Other than dirt/corrosion on the metal of the contacts, it might be that the problem is with the circuit that measures battery voltage (e.g. perhaps the unit is incorrectly reporting low battery).

I’d start with a torch that has a reasonably directed beam (e.g. most LED torches), and one of those flexible drain cleaners (springy steel band you uncoil to use) that can be had from most pound shops. Poke around until you can at least see the tube. Then, a kids fishing net might get it out with a bit of persistence. Or perhaps a litter-picker, modified with two halves of an old kitchen sponge stuck to the inside of each pincer (i.e. to give a wider grip surface). Or some combination of the two – you’ll need to get creative!